Sunday, May 22, 2011

App Engine's Price Shock and the New Web App Equilibrium

App Engine's Price Shock

The Google App Engine blog announced that Google's App Engine is moving out of beta this year. According to the blog this means that App Engine will have to become financially attractive to Google, and therefore the corresponding upward revision in pricing. The details are intricate and affect customers (app developers) differently based on what services they use; the takeaway is that there is a reduction in the free-tier plan, a fixed monthly subscription fee, and a switch from billing based on CPU cycles to billing based on CPU-instance uptime. Now this has made several app developers unhappy because they feel slighted by Google changing the pricing structure, so much, so late. Google is trying to assuage developer anger, but I am guessing that Google App Engine stands to loose many apps and developers given these higher pricing structures.

Anyway, going back to the 3 highlights of the pricing change, lets see how it improves App Engine's business plan.

Reduction of the free-tier - Google claims that the free tier was eating into App Engine resources because there are many non-paying apps that run just fine using these free resources. Google is out to trim the free tier, leaving just enough to still win over developers who want to experiment with the App Engine, but no more. If an app is seriously deployed, it needs to pay for App Engine real estate. Many apps running on the App Engine are back-ends to iOS and Facebook apps. Why should Google be bank-rolling apps that benefit those platforms? App Engine's early adopter phase is over and freebies can end.

Fixed $9 monthly subscription fee - The App Engine has been a fantastic success with more than 100K deployed apps. Even if 10% of them can be converted into monthly subscriptions then the App Engine will have an evergreen revenue stream (many developers have complained that they would end up pay much more than $9pm given the new pricing model).

CPU-instance time billing - Google wants customers to pay for availability (keeping their web apps running 24 x 7) rather than the amount of computation used by the apps. Since web apps usually remain online throughout, it makes business sense for Google to charge for this 24x7 CPU-instance time. CPU-cycles usage can be little and far-between given the eccentric product life-cycle, usage variability, and popularity of apps. It makes perfect sense for Google to start charging for availability rather than CPU cycles.

Off course these facts are not lost on other cloud providers such as Amazon's AWS service who have always charged per CPU-instance and offer lean free tiers as well.

The Equilibrium Shift

I don't expect developers to shun the App Engine (or other cloud services for that matter) given this and future price increases. Its much more expensive, both in terms of capex and opex, to achieve a cloud provider's level of service availability and convenience for small and mid-sized app shops. But these price changes will affect the technology and architecture decisions of app developers, here is how:

Simplification of server-side logic, and richer client side logic - Clever web app design can off-load CPU cycles to web-browsers, more so with the advent of sophisticated client-side Javascript libraries and HTML5. I expect web app developers to aggressively move more processing into the user browser. This has the added benefit of more responsive web applications, for example HTML5's local data store can be used to store user data and shave-off network latency.

Space-CPU time trade-off - Storage space continues to be relatively cheap in the cloud. I expect developers to store a lot more application state rather than having to compute it again at a later time. For example, instead of using traditional RDBMS databases (e.g. MySQL), app developers may start looking at simple nosql alternatives like couchDB, which are instead optimized to store multiple indexes and views based on common read patterns.

QoS as a service - App developers will also move toward higher workload thresholds in their load-balancing algorithms, meaning that users may see web apps slowing down as new CPU instances are more sparingly fired up during times of greater demand. I expect app developers to start charging users for differentiated QoS in apps. After all, there is no free lunch, and lunch just got a whole lot more expensive.

Availability as a service - Does it make sense for an app to keep its back-end running (CPU instances online) in the dead of night because 0.1% of its users are insomniacs? I think that some web apps may start experimenting with the breaking the unwritten rule of 24x7 web uptime, or at least charging more for the privilege of using these services outside waking hours. Off course, different time-zones complicate this idea.

In the end, money matters. Its going to be interesting to see the market affecting cloud-deployed web app architecture decisions of the future.